Electrocapillary device



May 6, 1930. M. LATOUR ELECTROCAPILLARY DEVICE Filed March 5, 1929 A TTOHNEVS currents into soundwaves,

Patented May 6,. 1930 UNITED STATES MARIUS LATOUF, OF SAN SEBASTIAN, SPAIN w ELECTROOAPILLA BY DEVICE Application filed March 5, 1929, Serial 1%. 344,280, and in ir-eat Britain August as, 1928.

tion of the contacting surface produces a corresponding variation in the potential difference of conduct.

The present invention relates to various apparatus, whose mode of operation is based on the above recalled phenomena and whose aimis either to transform, as in the case of microphones, sound waves into electric currents, or to transform, as in the case of telephone receivers and loud speakers, electric or else to detect electric oscillations.

From a historical point of-view, it must be recalled that the principle of the invention has already been indicated in the work of Comte du Moncel Le telephone, le microphone, et le phonographe 1878, which was translated into English in 1879 (see page 110/113 of this translation).

- Various forms of embodiment of the apparatus according to the invention have been represented, diagrammatically and merely by way of example on the appended drawing in which:

Fig. 1 is a sectional elevation'of one form of construction of the apparatus.

Fig. 2 shows another form of embodiment.

Fig. 3 shows the connection in parallel of various elements similar to that of Fig. 2.

Figs. 4 and 5 show different constructional forms.

Fig. 6 shows the series connection of several elements similar to that of Fig. 1,

Fig. 1 represents an embodiment of an electrocapillary microphone. A capillary tube 1,

-whose inner section increases, towards the upper opening, according to an exponential law, dips into the mercury 2 after having been filled with an electrolyte 3 (salt water, acidulated Water,- or the like) covered in its turn with a layer of oil 4 to prevent evaporation.

are connected to the primary of A conductor 5 is led from the electrolyte and a conductor 6 from the mercury,

The conductors 5 and 6, of acid proof metal,

a. transformer through the intermediary, or not, of l a potentiometer.

It will be easily'understood that the deformations of the upper surface of the electrolyte, which result from the action of sound waves, produce corresponding-deformations in the cont-acting surface of the meniscus 7 of the capillary tube, and, consequently, corresponding variations of p0= tential difference between the conductors 5 and 6.

A very satisfactory sensitiveness and quality of reproduction is obtained with a tube whose inner diameter ((1), measured at a height (h), calculated from the lower end when considered as a basis line, is a function of this height, which may approximately berendered as:

' d=d e with d =0.7 mms.

a=0.05 (h being calculated in mms.) (total) 50 mms. a

By making use only of salt water, of 5% (by weight), as electrolyte, it will be found that the impedance is of the order 1.606 ohms for a frequency of 800.

Fig. 2 represents a further embodiment of the invention in which the contact with the electrolyte is obtained by an acid proof metallic surface of large area in order to reduce the impedence of the double surface electrolyte-contact.

The meniscus is situated inside a calibrate ca illary glass tube 8, connected to a metallic tu e 9 (of nickel, iron nickel alloy, ironnickel-chromium or the like which is unattackable by the electrolyte 10 and which forms a cavity having a section which diverges towards the upper opening, substantially in accordance with an exponential law. The metallic portion is of course insulated on the outside and eventually provided with a. depth regulator allowing the position of the meniscus to be suitably fixed thereby reducing the electric losses of the liquidcolan. For setting purposes, it will be suffiant, for example, to mount the tube 9, in ch a manner as to be in slight frictional ding contact within the stopper 14, so that is vertical tube may be moved. The stopr 14 is furthermore providedwit-h a hole This device, of which several similar units 1y be reproduced, lendsitself to the conction of several elements in serlesor 1n rallel in which the elemental impedances' ould be equal, and the variations in the eleantal electric voltages should be equal and phase.

Fig. 3 represents an assembly of seven eleants mounted in parallel, such as A, B, C,

ie; the mercury may be held, by capil rity, in the tube, or tubes, whose dimen- 1 ins shall have been modified if need be; for ample, the coefficient characterizing the v of progressionof the inner section of the are or tubes may be modified.

Figs. 4 and 5 represent embodiments of the per part of the capillary tube in which a transmission of vibrations between the and the upper surface 'of the liquid 12 itained in the capillary tube 11, is effectthrough the medium of a thin diaphragm of suitable shape, resting on the upper face of the liquid. Ihe devices shown, by way of example, Figs. 1, 2, 3, 4, 5 and 6, are reversible and .y be utilized for transforming, as in the :e of telephone receivers and loud speakvarying electric currents into sound ves. it will be noticed that the devices accordto Figs. 1, 2, 3, 4, 5 and 6 may also be utiad to directly transform modulated highquency waves into sound waves, or operate elephone receiver by means of the moduion frequency without there actually bej electricv detection of the high frequency. ;his case, modulated high-frequency waves directly transformed into sound waves. t is, indeed, known that the electrocapily function of mercury whose surface is ered by an electrolyte may, upon first )roximation,be rendered in the form A being the value of the capillary connt' for the potential difference V applied between the mercury and the electrolyte and A K and V being constants.

An alternative potential difierence sin wt produces an average displacement of level of the meniscus, contained in one capillary tube, proportional to the variation of the capillary constant (AA)alt-= -'-KU The potential difference actually applied in the immediate proximity of the-contacting surfaceis not the total potential difference applied to the terminals of the device which may be represented diagrammatically by two resistances: one inseries with, the capacity of the contacting surface, the other in parallel therewith, representing the losses.

It will finally be noticed that if the electrolyte' is constituted by sea water, the apparatus described may be directly utilized for submarine telegraphy and telephony for all sound and ultra-sound-wave frequencies without the use of any other medium.

It is moreover self-evident that the invention has only been describedandrepresented herein a merely explanatory, but by no means limitary,' manner and that it could be subjected to various modifications of detail Without departing from the spirit thereof.

Iclaim:

1. Electrocapillary device adapted to be used either for the transformation 'of sound waves into electric currents, or conversely, or for the detection of electric oscillations, comprising in combination: a jar containing a good conducting liquid, a tube dipping, at itsrlower end, into said conducting liquid and containing an electrolyte the upper surface of which is substantially ona level with the upper edge of the tube and is free to vibrate, the inner section of this tube, which is capillary at the lower end, diverging towards the upper part according to an exponential law, and means for electrically connecting, to'the external electric circuit, on the one hand, the conductingliquid, and, on the other hand, the electrolyte.

2. Electrocapillary device adapted to be used either for the transformation of soundwaves into electric currents, or conversely,

or for the detection of electric oscillations,

comprising in combination: a 'ar containing a good conducting liquid,a tu e dipping, at

its lower end, into said conducting liquid andcontaining an electrolytethe upper surface of which is practically on a level with the upper edge of the tube and is free to vibrate, the inner section of this tube, which is capillary at the lower end, diverging towards the upper part accordingto an exponential law, a thin and projecting dia-' phragm resting on the upper surface of said electrolyte in order to improve the transmission o f the vibrations between this upper 'waves into electric currents, or conversely,

or for the detection of electric oscillations, comprising in combination: a par containing a good conducting liquid, a tube of glass or other insulating substance containing an electrolyte the upper surface of which is practically on a level with the upper edge of the tube and is free to vibrate, the inner section of'this tube, which is capillary at its lower end, diverging towards the upper part according to an exponential law and two conducting wires penetrating respectively within the conducting liquid and the electrolyte, and connected to the terminals of the external circuit.

4. Electrocapillary device adapted to-be used either for the transformation of sound waves into electric currents, or conversely, or for the detection of electric oscillations, 'com prising in combination: a jar containing a good conducting liquid, a tube wholly or in a great measure metallic, dipping at its lower end in the conducting li uid and containing electrolyte the upper sur ace of which is free to vibrate, the inner section of this tube diverging towards the upper endaccording to an exponential law, a calibrated glass tube fixed to the lower art of the metallic tube and the section of which is capillary and joins the inner section the metallic tube, an insulating sheath surrounding the lower end of said metallic tube to isolate the same electrically from the conducting liquid, a conducting wire electrically connecting the conducting liquid to one of the terminals of the external circuit, and a conducting wire electrically connecting the metallic tube to the other terminal of said circuit.. c

5. Electrocapillary device adapted to be used either for the transformation of sound waves into electric currents, or 1 conversely,

or for the detection of electric oscillations,

comprising in combination: a jar containing a good conducting liquid, a tube wholly or in a great measure metallic, dipping at its lower end in the conducting liquid and-containing an electrolyte the upper surface of which is free to vibrate, the inner section of this tube diverging towards the upper end according to an exponential law, a calibrated glass tube fixed to the lower part of the metallic tube and the section of which is capillary and joins the inner section of the metallic \tube, an insulating sheath surrounding the lower end of said metallic tube to isolate the same electrically from the conducting liquid, means for regulating the height of the metallic tube and in consequence, the calibrated 'into said electrolyte an ducting liquid the upper surface of which is glass tube with regard to the level of the conducting liquid, a conducting wire electri-- cally connecting the conducting liquid to one of the terminals of the external current, and

a conducting wire electrically connecting the metallic tube to the other terminal of said circuit.

6. Electrocapillary device adapted to be used either for the transformation of sound waves into electric currents, or conversely, or for the detection of electric oscillations, comprising in combination: a jar containing mercury, a tubedipping, at its lower end,

into said mercury and containing an acid or salt solution the upper surface of which is substantially on a level with the upper edge of the tube and is free to vibrate, the inner section of this tube, which is capillary at its lower end, diverging towards the upper part according to an exponential law, and means for electrically connecting to the external electric circuit, on the one hand the mercury and, on the other hand, the acid or salt solution. v I

7. Eclectrocapillary device adapted to be used either for the transformation of sound waves into electric currents, or conversely, or for the detection of electric oscillations, comprising in combination: a jar containin an electrolyte, a'tube dip ing at its lower en containing a consubstantially on a level with the upper edge of the tube and is free to vibrate, the inner section of this tube, which is capillary at the lower end, diverging towards the upper part according to an exponential law, and'means for electrically connecting to the external electriecircuit, onthe one hand the conducting liquid and, on the other hand, the electrolyte.

8. Electrocapillary device adapted to be used either for the transformation of sound waves into electric currents, or conversely,

or for the detection of' electric oscillations, comprlslng 1n comb1nat1on: aseries of jars containing a good conducting liquid, a series of tubes dipping, each at its lower end, into said conducting liquid of one of saidjars and Z containing an electrolyte the upper. surface of which is free to vibrate, the inner section of each of these tubes, capillary at the lower end and, diverging towards the upper art according to an exponential law,*a con ucting wire connecting the electrolyte of-the first tube to one-of the terminals of the external to the other terminal, and conducting wire connecting the conducting liquid of each jar to the electrolyte of the tube dipping in the following jar.

9. Electrocapillary device adapted to be used either for the transformation of sound waves into electric currents,-or conversely,

electric circuit, whereasanother wire oonnects the conducting liquid from the last jar or for the detection of electric oscillations, I

comprising in combination: a jar containing a good conducting liquid, a'seri'es of tubes communicating through their upper parts and dipping each at its lower end, in said conducting liquid and containing an electrolyte the upper surface of which is free ,to' vibrate, the inner surface of each of'these tubes, capillary at the lower end, diverging towards the upper part according to an exponential law, means, such as an. insulating sheath, for insulating, on the'outs ide, each of the tubes of the conducting liquid, and

means for connecting in parallel the electro lyte of eachof said tubes to one of the terminals of the external circuit, the other terminal of which is' connected to' the conducting liquid. i

V MARIUS LATOUR. 

